We propose to continue our investigation of the immunologic characteristics of human colostral lymphocytes in the following general areas: (1) The alloractivity of colostral T cells will be assessed in mixed lymphocyte reaction and cell-mediated lympholysis assays, and special attention will be paid to reactivity toward the paternal HLA haplotype. Regulation of this activity will be investigated. (2) Using a rabbit model we will be examining the parameters leading to the effective immunization of the mammary gland, particularly that expressed by resident cells. (3) We have also developed at a rat model to examine lymphocyte migration to the mammary gland and will concentrate our efforts on assessing T cell involvement in this process.